The present invention relates to a self-locking safety belt reeling device with a vehicle-sensitive and/or belt-sensitive controllable blocking device and with a tightening device acting on the safety-belt reeling shaft, comprised of a drive disk which is to be driven in rotation by a drive device, which drive disk, upon activation of the tightening device can couple via a tightener coupling with the safety-belt reeling shaft.
A safety belt reeling device of the aforementioned kind including a coordinated tightening device is known from German Offenlegungsschrift 34 07 378. In the known device the safety-belt reeling shaft can be coupled with a clutch disk connected thereto to a cable pulley (drive disk) from which cable pulley a cable can be removed by a pyrotechnical linear piston drive. Upon rotation of the cable pulley a radially pivotable pawl is pivoted outwardly and engages the clutch disk connected to the safety-belt reeling shaft. After completion of the tightening movement a return movement of the safety-belt reeling shaft by a small amount in the direction of removal of the safety-belt results in a direct pivoting of the locking member of the self-locking safety belt reeling device so that upon further load resulting from removal of the safety-belt the safety-belt reeling shaft is blocked and no further removal of safety-belt is possible.
Following the blocking of the safety-belt reeling device as a consequence of the tightening step it is possible that considerable forces result when the person using the safety-belt is forced into the safety-belt due to acceleration or deceleration forces acting on the body and there is a risk of being injured by the safety-belt upon being retaining therein. Especially in connection with an airbag which during an accident additionally buffers a forward movement of the passenger buckled in with the safety-belt, it is now desirable that to a certain extent, even after actuation of the safety-belt reeling device and blockage of the further removal of the safety-belt, a certain amount of forward movement of the person buckled in should be possible. This forward movement can be used in connection with the blockage of the safety-belt reeling device and the subsequent loading by the body of the passenger in order to reduce power peaks, respectively, to dampen the retaining impact.
A power limiting device for a safety-belt is already known from German Offenlegungsschrift 20 26 277. In the known device the power limiting device is in the form of a torsion rod. The torsion rod is integrated into the safety-belt reeling device. However, in the prior art the reeling device is a simple storage device for the safety-belt without its own winding or locking device. The torsion rod is on the one hand connected to the housing of the safety-belt reeling device connected to the vehicle and on the other hand to the shaft that supports the wound safety-belt. During loading upon removal of the safety-belt from the shaft the rotation of the shaft is braked by the torsion rod and the force level is lowered. A corresponding device is also known in conjunction with a self-locking safety-belt reeling device from German Patent 20 47 842. In these prior art devices, however, a functional connection to the tightening device integrated into the safety-belt reeling device is not present. It should be noted in this context that the tightening device may not drive the shaft of the safety-belt reeling device via the power limiting device because for powerful tightening devices the power limiting device may already be activated during safety-belt tightening.
It is therefore an object of the present invention to provide a safety-belt reeling device of the aforementioned kind that includes a tightening device and with which it is possible to allow for a limited forward movement of the person buckled in depending on an operational condition in order to reduce occurring high loads.